Introduction: Among all hypertensive disorders, preeclampsia is as a multisystem disorderandit is the major and prevalent factor for defection or death in the fetus and mothers. There are many evidence regarding damage of endothelial cells and change in their function that might have important role in pathogenesis of preeclampsia. Most of the researches has been focused on the role of Vasoactive Eicosanoids .In addition, Nitric Oxide as a vasodilator componenthas important role during pregnancy. Therefor, the present study was designed to comparationlevel of NO, TXA2, PGE2 and PGI2 in plasma among normal and preeclampsia pregnant women. Material and Methods: In this study, blood samples were collected from 40 pregant women and 40 pregnant with preeclampsia. The Nitrite and Nitrate (NO2-/NO3-) the stable and product NO in plasma were measured by colorimetric method (Griees reaction). The stable metabolits of thromboxane A2 (thromboxane TXB2), PGI2 (6-keto- prostaglandin Fla) and PGE2 in plasma sample were measured by reverse- phase HPLC in ng/ml level. Statistical analysis was performed using T-test and SPSS software. Results: the level of NO in the plasma of preeclampsia group was 36.22 ±5.4 µmol/l as compared to normal group (56.72±11.3) µ mole/l and PGI2, PGE2 and TXA2 in the palsma of preeclampsic women were 22.35±14.40, 92.57±46.18 , 2082.25±694 ng/ml respectively. meanwhile the level of them for control (normal) group were 118.07 ± 39.81(P<0.001), 240.92 ± 122.87(P<0.001) and 450.22 + 330.93(P<0.001), respectively, The ratio of TXA2/PGI2, used to express relative vasoconstriction vs. vasodilation effect, was 83% higher in preeclampsia women to normal pregnant women (P<0.001). Conclusion: The result of this study showed the significant reduction of NO, PGI2 a ,PGE2 and an increase in TXB2 in preeclampsia as compared to normal pregnant women, which- suggests the possible role of above compounds in the pathogenesis of preeclampsia. Thus the measurements of these compounds study the levels of nitric (NO) thromboxane A2 (TXA2) prostaglandin E2 (PGE2) and prostacyclin (PGI2) in plasma of normal. Could be useful in diagnosis of early- preeclampsia and possible control of these factors or prevention of side effects of preeclampsia.